Island



PATENTED JAN 141868 vif i554 A IL/f v@with gieten gateut @ffice- THEODOR. G. EISWALD, OF PROVIDENCE, RHODE ISLAND. `*Letters Patent No. 73,311, dated Janitary 14, 1868.

IMPROVEMENT IN SAFETY-PLUGS FOR BOILERS.

TO IJL WHOM IT MAY CON CERN:

vBe it known that I, lnnonon G. ElswALD, of Providence, in the county of Providence, and State' of Rhode Island, have invented a new and improved vSafety-Plug for Boilers; and I do hereby declare tliat the following is a -'ull, clear, and exact description tbereotQ-which will enable those skilled in the art tomalke and use thev same, reference being had to the accompanying drawings, forrningpart oi' this specification, in which- Figure 1 is a plan view of my invention. ,l

Figure 2 is a. section of the same through the line :v zu', g.'1.

Similar letters of reference indicate correspondingparts.

This invention refersv toan improved fusible plug for boilerspand 'consists in the construction of the holes for containing the fusible metal plugs, which are conical, so that the said plugs shall not be blown out by the pressure ofthe steam, together with other devices perfecting the' whole, aswill be hereinafter more fully set forth. I

In the drawings, 'A is a Aflanged. hollow nut tapped into the'boiler at the low-water level. A screw-cap, B, fits on the'said nut stem-tight. In this cap are one. or more. small conical holes, as shown thedruwing. These holes are lled with a fusible'alloy, or common solder,.of Asuch a. melting-point that when theiwater falls below the nut the 'u'sible alloy will melt out,and tbe escape ofxsteam will call attention to the low state of the water in time to prevent disaster, A-by applying the feed-pumps. Duplicate caps can be provided, so that another cap vwith similar plugs can be applied without waiting to re-plug the cap previously used.' i I am aware that fusible plugs have been employed forthe purpose of permit-ting the escape of steam when the same was at too great a pressure for safety, but in all such cases the arca ofl the plug was largo, and thc escape of steam in sufficient quantity to relieve the boiler was theobject intended. The pointsof application of such fusible plugs were gn top of the boiler, for considerably above the highest water level, and their action was not'specifically dependent upon thev fall of the water per se, so as to permit the escape of a small quantity of steam for the purpose of calling attention to the'low state of the watcr in the boiler.

Certain disadvantages attend the use of such fusible plugs as are above cited, as, for example, they are liable to become honey-combed, so called, .by the gradual melting out of the softest metal in the alloy, thus rendering them useless for the purpose intended. Their action, also, is unreliable, as they-frequently melt out at different degreesof,steam-pressure. Furthermore, the sudden escupe of steam when the water hns fallen below the fines oecasions the rising of the .water on the hot lues, and thereby causing the'explosion of the boilers. These disadvantages are obviated by my invention, which gives a reliable and timely warning, that cannot be mistaken or overlooked, as the alloy composing the plug is nearly any common solder that will melt when unprotected by contact with water.

I claim as new, and desire to secure by Letters Patent- Fusible plugs, constructed substantially as shown yand described.

' THEODOR G. EISWALD.

Witnesses:

J. M. ADDEMAN, ERVIN T. CASE. 

